Although numerical control has greatly improved the speed, reliability and consistency with which workpieces may be machined, cut, welded or otherwise operated upon, many manufacturing and repair tasks remain time consuming operations. For example, high pressure turbine blades used in aircraft jet engines are susceptible to tip wear. Presently, tip repair of engine run parts is a time-consuming task in which build-up welding is applied manually by a skilled welder to the blade tip of the turbine blade. Automation of this process has been difficult due to the non-uniformity of turbine tip wear and variations in blade tip surfaces from blade to blade which require adjustment of welding parameters prior to each blade repair. Attempts to automate the tip repair Process through the application of computer aided design (CAD) techniques to define a weld path have resulted in inconsistent blade tip repairs due to the variations in tip wear and differential stresses from blade to blade.
Many automated machine systems employ probing systems for verifying workpiece location or dimensions, with probe results thereafter utilized to determine offsets to be applied to nominal workpiece dimensions or coordinates. For example, coordinates defining the location of a hole to be drilled in a workpiece may be adjusted after a probing cycle to maintain the hole location at a predetermined distance from a part edge. Non-contacting, probe-less inspection systems, referred to herein as vision systems, have similarly been employed to verify workpiece location or dimensions. In addition, vision systems have been used in the past on relatively simple objects to recognize and verify object shapes. Some automated machine systems utilize the results of this recognition step to select machine programming for execution or to retrieve predetermined process parameters from storage in a memory device.
The present invention contemplates a vision system which differs from the above described prior art probing systems and vision systems in that the system described below actually measures and mathematically describes the geometry of a workpiece and generates process parameters from an image of the workpiece surface.